Seaming apparatus connect side edge portions of adjacent panels with an interlocking seam. Seaming apparatus heretofore provided include rollers that bend a side edge portion or terminal section of connecting flange portions of two adjacent panels, and opposed guide rollers that support the side edge portions and oppose the force of the seaming operation perpendicular to the axis of travel. The seaming operation creates a reactive force on the forming rollers opposite the direction of travel, so a forming roller must be rigidly fixed relative to the seamer along this axis. In order to provide consistent, quality seams, the forming rollers and guide rollers require fixed, rigid positioning relative to each other both in the direction of travel and perpendicular to the direction of travel.
Seamers heretofore provided have been patterned after conventional roll-forming apparatus. Typical features of prior known seamers include pairs of directly opposed rollers and multiple, sequential roller pairs. Since a single pair of directly opposed rollers is inherently unstable, prior known seamers have at least two pairs of rollers. Seamers with multiple, sequential roller pairs are disclosed U.S. Pat. No. 3,610,191 to Harris, U.S. Pat. No. 3,771,482 to Thompson, U.S. Pat. No. 4,324,031 to Isenhoff, U.S. Pat. No. 4,918,797 to Watkins et al., and U.S. Pat. No. 4,726,107 to applicant.
In prior known seamers, the pairs of rollers are often progressive from one pair to the next, making the seamer unidirectional. A seamer with progressive rollers cannot seam to the end of the panels and can only seam to a point relative to the end of the panels equal to the distance between the leading and the last roller pair. If the pairs of rollers are not progressive, the seamer can be bi-directional but the seamer includes duplicate, redundant roller pairs. Bi-directional seamers are disclosed in U.S. Pat. No. 4,989,308 to Sanders and U.S. Pat. No. 4,470,186 to applicant.
Prior known devices that relate to stringing power cables have used a triangular three roller configuration and include U.S. Pat. No. 728,768 to Salisbury and U.S. Pat. No. 2,786,092 to Gage. The device in Salisbury would not be suitable for seaming panels since the device does not have a fixed operating position for the single roller and cannot provide uniformity between seams on different panels. Also, the forming force parallel to the direction of seamer travel would rotate the single roller away from the other rollers in the Salisbury device. The device in Gage uses a spring to bias the single roller toward the opposing pair of rollers so that the seam shape with the Gage device would be dependent on the speed the device is moved along the panels edges. The Gage device does not have a fixed operating position for the single roller and would not be suitable for seaming panels.